Needle clamp for sewing machines

ABSTRACT

A needle clamp for a sewing machine is disclosed comprising a resilient needle gripping member and means for deforming the resilient member into an operative needle gripping condition.

United States Patent inventors Appl. No. Filed Patented Assignee NEEDLECLAMP FOR SEWING MACHINES Primary ExaminerRichard J. Scanlan, Jr.Attorneys-Marshall J. Breen, Chester A. Williams, Jr. and

Robert E. Smith sclaimsflnrawing Figs ABSTRACT: A needle clamp for asewing machine is dis- U.S.Cl 112/226 Closed comprising a resilientneedle gripping member and Int. Cl DOSb 55/02 means for deforming theresilient member into an operative Field of Search 112/226 nee e grippng co dition.

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IN VEN'I'URS William E Caplan Edmund B.Wilsonlll fiyw e Kim,

nnmrv NEEDLE CLAMP FOR SEWING MACHINES SUMMARY OF THE INVENTION Thisinvention relates to a clamping device for fastening a sewing needle tothe needle bar of the sewing machine in proper relation to the looptaker.

Heretofore it has been necessary for a sewing machine operator to turn aneedle clamp thumbscrew a plurality of revolutions in order to engagethe needle shank when fastening a sewing needle in the needle clamp.During the course of turning the thumbscrew the operator may, onoccasion. improperly hold the sewing needle in fastening positionrelatively to the thumbscrew and either drop the sewing needle or failto internally seat the needle shank the full axial depth of the clampbore.

Dropping the sewing needle is not only frustrating but may result indamage and serious impairment of the stitch forming instrumentalitiesshould the needle penetrate the needle hole in the throat plate andbecome lodged in such a way as to possibly damage the loop takermechanism. In addition, should the operator fail to internally seat theneedle shank the full axial depth of the clamp bore, the operator uponattempting to sew may find that the needle thread loop thrown out by thesewing needle is'improperly aligned proximate the needle thread seizingbeak of the loop taker, which misalignment will result in the skippingof stitches or in a complete failure to form stitches.

It is therefore an object of the present invention to provide a needleclamp which will minimize the aforementioned undesirable conditions bymeans of structure readily accessible for manipulation permitting aquick-fastening of the sewing needle to the needle bar.

It is another object to employ means for deforming a resilient needlegripping member which is constrained in a recess formed in the lower endofthe needle bar, resulting in a structural redistribution of theresilient member in a manner to grip the shank of a needle inserted intothe resilient member.

It is further object of the invention to provide a needle clamp whichassures that the sewing needle can only be inserted in correct relationto the loop taker.

A further object of the invention is to provide a clamp which firmlysupports the sewing needle.

DESCRIPTION OF THE DRAWINGS With the above and additional objects andadvantages in view as will hereinafter appear, this invention comprisesthe devices, combinations, and arrangements of parts hereinafterdescribed and illustrated in the accompanying drawings of a preferredembodiment in which:

FIG. 1 represents a perspective view of the lower portion of the sewinghead illustrating the present invention in its needlegripping position;

FIG. 2 represents an exploded perspective view illustrating the presentinvention;

FIG. 3 represents an enlarged elevational view illustrating theassembled form ofthe present invention;

FIG. 4 represents a vertical cross-sectional view of FIG. 3;

FIG. 5 represents a horizontal cross-sectional view taken substantiallyalong line 5-5 in FIG. 4;

FIG. 6 represents an enlarged horizontal cross-sectional view takenthrough line 6-6 in FIG. 4; and

FIG. 7 represents a view illustrating the development of the slottedcamming portion ofthe clamping band.

DETAILED DESCRIPTION OF THE INVENTION The present invention as shown inFIG. 1 is illustrated as embodied on a conventional sewing machinehaving a frame including a work-supporting bed 11, over which issupported a bracket arm (not shown) terminating in a sewing head 13.Slidably supported for vertical movement in the sewing head 13 is aspring depressed presser bar 15 carrying at its lower end a presser foot17. Supported for endwise reciprocation in the sewing head 13 is aneedle bar 19 carrying at its lower end a needle 21 by means ofa needleclamp 23.

The needle bar 19 is formed with an axial recess 25 in its lower endconstraining a resilient needle gripping insert 27. The resilient insert27 is semicylindrical in form including an axially disposed open channel29 formed with a flat bottom wall 31 and a rounded sidewall 33, as shownin FIG. 6.

Also supported internally of the recess 25 is a rigid needle carrier 35semicylindrical in form and including a key 37 radially projecting fromits outer surface. The key 37 is adapted to coact with a key slot 39formed in the lower end of the needle bar 19.

The needle carrier 35 is formed with an axially disposed open channel 41having a flat sidewall 43 and a flat bottom wall 45 disposed at an acuteangle relative to the sidewall 43, as shown in FIG. 6. The lower portionof the needle carrier is cylindrical and provides an abutment face 47eomplimental in form to the resilient insert 27, which abutment face 47axially bears against one end of the resilient insert 27 when the needleclamp is assembled.

The flat bottom wall 31 of the resilient insert 27 coacts with the flatbottom wall 45 of the needle carrier 35 to receive the slab side 49 ofthe needle 21, which structure cooperatively functions, together withthe key 37 and keyslot 39, to assure the correct positioning of thesewing needle 21 relative to the loop taker (not shown).

A clamping band 51 formed with a cylindrical bore 53 rotatably embracesthe lower end of the needle bar 19. The clamping hand 51 is formed withan inclined camming slot 55. Projecting through the camming slot is ascrew pin 57 which is threaded into a tapped hole 58 in the needle bar.The pin 57 secures the clamping band SI on the needle bar with capacityfor turning movement, and because of the inclination of the camming slot55, the clamping band when turned counter clockwise as viewed in FIG. 1,will shift axially upward relatively to the needle bar. To provide forturning the clamping band the latter is provided with a thumb grip 59which when in its needle secured position can additionally function as adriving element for the usual needle bar actuated attachment. As shownin FIG. 4, the bore 53 at the lower extremity is formed with an inwardlyextending flange 60 in which a needle clearance aperture 62 is provided.The needle carrier 35 is supported on the flange 60 so that as theclamping band shifts upwardly when turned counterclockwise, the carrier35 will also be shifted upwardly so as to compress the resilient insert27.

In the operation of the preferred embodiment, the operator can insert aneedle 21 through the axially formed clearance aperture 62 in theclamping band 51 in only one orientation, i.e., with the slab side 49 ofthe needle 21 in register with the mutually aligned flat bottom walls 31and 45 of the resilient insert 27 and needle carrier 35, respectively.The operator then turns the clamping band 51 by swinging the thumb grip59, thus causing the clamping band 51, through the action of the cammingslot 55 on the screw pin 57, to shift upwardlyalong the needle bar 19.

As the clamping band 51 moves upwardly, the flange 60 shifts the needlecarrier 35 upwardly and the abutment face 47 of the needle carrier 35axially bears against and compresses the resilient insert 27. Theresultant deformation of the resilient insert 27 effects a progressiveradial deformation of the channel 29 and therefore a radial gripping ofthe needle 21 by the resilient insert 27.

It will be understood that only a minimal angular displacement of thethumb grip 59 is necessary to change the resilient insert 27 from one ofrelaxed inoperative condition to one of operative needle grippingcondition.

Inasmuch as sewing needles in various sizes are used, the camming slot55 includes a plurality of transversely formed locking grooves 61-61adapted to coact with the pin 57 to provide detent means for lockingneedles differing in shank diameter.

From the foregoing description it is apparent that, in principal, theneedle clamp disclosed herein utilizes structure for deforming aresilient member from a relaxed inoperative condition into an operativeneedle gripping conditions It will be understood that the aforementioneddisclosure is merely a description of a preferred embodiment foraccommodating a progressive deformation ofa resilient needle grippingmember and is not to be construed as limiting the spirit of thisinvention.

Having thus set forth the nature of this invention, what I claim hereinis:

1. In a sewing machine having a frame, a needle bar supported in saidframe for reciprocation in an endwise path, a needle clamp comprising aresilient needle gripping means, means associated with said needle barfor constraining said resilient needle gripping means, a clamping bandrotatably embracing said needle bar, said clamping band formed with aninclined camming slot, means projecting from said needle bar andengaging said needle bar engaging feed camming slot to shift clampingband axially along said needle bar when said clamping band is turned,and support means carried on said clamping band for effectingprogressive deformation of said resilient clamping means when saidclamping band is turned relatively to said needle bar.

24 A needle clamp as set forth in claim wherein said needle bar includesa cavity in which said resilient needle gripping means is confined, saidcavity being formed with a slotted keyway, said clamping band includinga needle carrier formed with a key adapted to coact with said keyway,said needle carrier including a needle accommodation channel formed witha flat sidewall and a flat bottom wall disposed at an acute anglerelative to said flat sidewall, said channel in said needle carrierterminating in abutment means for deforming said resilient needlegripping means, said resilient needle gripping means in engagement withsaid abutment means and formed with a needle accommodation channelhaving a flat bottom wall adapted to coact with said flat bottom wall ofsaid needle carrier for receiving a flat-sided needle shank.

3. A needle clamp as set forth in claim 1 wherein said camming slotincludes a plurality of locking grooves transversely formed thereinadapted to coact with said projection means providing a detent forlocking sewing needles having shanks differing in a diametral size.

1. In a sewing machine having a frame, a needle bar supported in saidframe for reciprocation in an endwise path, a needle clamp comprising aresilient needle gripping means, means associated with said needle barfor constraining said resilient needle gripping means, a clamping bandrotatably embracing said needle bar, said clamping band formed with aninclined camming slot, means projecting from said needle bar andengaging said needle bar engaging feed camming slot to shift clampingband axially along said needle bar when said clamping band is turned,and support means carried on said clamping band for effectingprogressive deformation of said resilient clamping means when saidclamping band is turned relatively to said needle bar.
 2. A needle clampas set forth in claim 1 wherein said needle bar includes a cavity inwhich said resilient needle gripping means is confined, said cavitybeing formed with a slotted keyway, said clamping band including aneedle carrier formed with a key adapted to coact with said keyway, saidneedle carrier including a needle accommodation channel formed with aflat sidewall and a flat bottom wall disposed at an acute angle relativeto said flat sidewall, said channel in said needle carrier terminatingin abutment means for deforming said resilient needle gripping means,said resilient needle gripping means in engagement with said abutmentmeans and formed with a needle accommodation channel having a flatbottom wall adapted to coact with said flat bottom wall of said needlecarrier for receiving a flat-sided needle shank.
 3. A needle clamp asset forth in claim 1 wherein said camming slot includes a plurality oflocking grooves transversely formed therein adapted to coact with saidprojection means providing a detent for locking sewing needles havingshanks differing in a diametral size.